The use of corneal imaging with hand-held and other devices such as mobile phones, smartphones, tablets, laptops, and the like, requires that a corneal imaging based interface must work reliably across a range of different operating conditions, including when eyewear such as glasses, spectacles, sunglasses, goggles, or a contact lenses, is worn by a user operating the device.
Corneal imaging is a technique which utilizes a camera for imaging a person's cornea, in particular that of the user of the device, for gathering information about what is in front of the person and also, owing to the spherical nature of the human eyeball, for gathering information about objects in a field-of-view which is wider than the person's viewing field-of-view. Such objects may potentially be outside the camera's field-of-view and even be located behind the camera. The technique is made possible due to the highly reflective nature of the human cornea, and also the availability of high-definition cameras in devices such as smartphones and tablets. An analysis of the characteristics of the corneal imaging system has been given by K. Nishino and S. K. Nayar, “Eyes for relighting”, in ACM SIGGRAPH 2004 Papers (SIGGRAPH '04), ACM, New York, 2004, pages 704-711.
Glasses may be worn to correct vision, for fashion, to avoid glare, or for protection, and are manufactured with a range of surface finishes that range from those which seek to avoid surface reflections to highly reflective coatings, and with various curvatures of lenses.
The use of eyewear, in particular such as prescription glasses or sunglasses, is likely to generate additional specular reflections originating from both the cornea of the user's eye and the glasses, or in the case of glasses with a highly reflective finish from the glasses alone. This may result in a corneal imaging system delivering erroneous results.